Linux多进程文件拷贝(C/C++)——方案二（使用mmap内存映射）
#include <iostream> #include <sys/mman.h> #include <unistd.h> #include <sys/types.h> #include <fcntl.h> #include <sys/stat.h> #include <string.h> using namespace std; int main(int argc,char* argv[]) { if(argc < 4) { cout << "Usage: ./a.out fileSrcPath fileDestPath processNumber" << endl; return 0; } int srcfd = open(argv[1],O_RDONLY); if(srcfd == -1) { perror("open src error"); return -1; } int len = lseek(srcfd,0,SEEK_END); //cout << "src len = " << len << endl; if(len == -1) { perror("lseek src error"); return -1; } char* ptr_r = (char*)mmap(NULL,len,PROT_READ,MAP_SHARED,srcfd,0); if(ptr_r == MAP_FAILED) { perror("mmap src error"); return -1; } close(srcfd); int desfd = open(argv[2],O_RDWR|O_CREAT,0664); if(desfd == -1) { perror("open des error"); return -1; } //也可以使用lseek，最后必须写点东西才行，否则会报Bus Error（总线错误） int ret = ftruncate(desfd,len); //cout << "des len = " << len << endl; if(ret == -1) { perror("ftruncate error"); return -1; } char* ptr_w = (char*)mmap(NULL,len,PROT_WRITE,MAP_SHARED,desfd,0); close(desfd); if(ptr_w == MAP_FAILED) { perror("mmap des error"); return -1; } int i; pid_t pid; //传进来的argv[3]参数是总进程数，所以创建argv[3]-1个子进程 int childPronum = atoi(argv[3])-1; //将文件分为总进程数量个块 int eachSize = len/(childPronum+1); for(i=0;i<childPronum;i++) { pid = fork(); if(pid == -1) { perror("fork error"); return -1; } else if(pid == 0) { break; } } //子进程拷贝前childPronum 份等长数据 while(pid == 0 && childPronum--) { if(i == childPronum) { memcpy(ptr_w+i*eachSize,ptr_r+i*eachSize,eachSize); cout << "child_" << i << "'s pid = " << getpid() << ",writes bytes = " << eachSize << endl; break; } } //父进程拷贝最后一份长度不确定数据 if(pid > 0 && i == childPronum) { memcpy(ptr_w+i*eachSize,ptr_r+i*eachSize,len-i*eachSize); cout << "i = " << i << " parent's pid = " << getpid() << ",writes bytes = " << len-i*eachSize << endl; } if(munmap(ptr_r,len) == -1 || munmap(ptr_w,len) == -1) { perror("munmap error"); return -1; } return 0; } 若有误请指出，谢谢